IEM ECE Electrovision 2013

Editorial
Prof. K. K. Ghosh
Head of the Department,
Editor, ELECTROVISION
I am extremely happy to know that the Dept. of Electronics and
Communication Engineering, IEM is bringing out their department magazine
during this year. In addition to the numerous achievements of the institute this is
yet another mile stone in their curricular and co-curricular activities. I hope the
magazine will bring creative talents of the students of the department. I wish them
all success. It was quite inspiring to watch and witness the potential of our
students unfolding at various stages and situations each day. Trying and testing
times during the hectic semester system have elicited our students to put forth
their best. The management and the staff have been supportive of the various
activities that were undertaken by the students in view of helping them reach the
pinnacle of perfection and professionalism in whatever task they took on, thus
strengthening our journey of achieving excellence. I sincerely express my
gratitude and thank the Director, Prof. Satyajit Chakrabarti, Principal, Prof. Dr.
Dipak Chatterjee , the entire editorial board, students and teachers who have
been of immense help in breathing life into these pages.

Electrovision 2013 Faculty Team
Prof. Malay
Gangopadhyay
Prof. Dr. G. S.
Taki
Prof. Gautam
Ghosh
Prof. Indranil
Basu
Prof. Partha
Sarathi Paul
Prof. Arindam
Chakraborty
Prof. Indrani
Bhattacharya
Prof.
Mili Sarkar
Prof. Ratna
Chakrabarty
Prof. Arunava
Mukhopadhyay
Prof. Rajib
Ghosh
Prof. Moloy
Narayan Das
Prof. Debadyuti
Ghosh
Prof. Tuhin
Utsab Paul
Prof. Srijita
Chakraborty
Prof. Anushyuta
Basu
Prof. Dr. K.K. Ghosh

About the Department
Institute of Engineering & Management (IEM) opens up the doors of young minds who dare
to dream. It encourages the spirit of free enquiry and imagination. Here dreams take shape.
The Institute tries to indicate the sense of human values and discipline to make students
respectful towards human beings, realise and demonstrate their best potential and be winners
in life. The Institute is affiliated to the West Bengal University of Technology (WBUT). B.Tech.,
M.Tech., MBA courses are approved by AICTE, Govt. of INDIA.
The Electronics and Communications Engineering (ECE) Department of IEM emphasizes
technical skills that can be used to help design, develop, install, test and maintain
communications systems. Students may begin to pursue career opportunities in a variety of
entry-level positions, such as electronics engineering technologist, electronics engineering
assistant, engineering sales/service representative, computer systems technologist, technical
consultant,telecommunications technician,communication systems installer, and field service
representative, engineering technician or research technician. Our top domain recruiters are
Ericsson, Vodafone, Bharti Airtel, Sankalp Semiconductor. The students may also sit for
placements in the IT sector companies. High ranking students from WBJEE and AIEEE take up
ECE at IEM because we strive to be an exciting place to learn and work, where no goal is too
ambitious to strive for, where nothing is too sacred to laugh at, and where everybody's ideas
count.

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# Trending now
Target Following
Autonomous Robot
Touch Screens
JavaScript-based Multiformat
Sudoku Puzzle Solver
Crossword @ Electrovision
Did You Know? – An Electrical Plug
Story
Photo Gallery
Gadget Speak
Internet of Things
Implementation of Fast Fourier
Transform Using C++
Security Products
CATOMS: Claytronic Atoms
Working With Temperature
Sensors: A Guide
Audio/Video Processors for
Embedded Multimedia Designs
Where Do Open Source Engineers
Fit in the Electronics Industry
Biochips
Website Design
Content, Graphics & Design : Agomoni Sarkar, Rajarshi Das
Contents

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#Trending now
- Neha Kapoor, B.Tech. 2013
Thin Air Writing
Modern research has given birth to an electronic glove that allows
you to write in thin air. It looks very similar to a fingerless bike
glove, but it has a built-in sensory computer program. This glove
has 17 electronic patches that are sensitive to feeling muscle
actions in your hand. It can recognize when you trace letters of
the alphabet.
Virtual Reality Mapping
New gaming software has taken a sensory leap for the blind. Virtual
games are being built to help navigate players through real buildings
and subway tunnels. This is done with a keyboard, using spectral
sounds to create spatial surroundings to offer a mapping system for
the blind.
Touching Holograms
Japanese scientists are steps away from creating technology that will
display a hologram and allow you to actually feel it. Most holograms
are seen on credit cards or DVD cases. Now, scientists have created
ultrasonic waves that can simulate a certain field of real pressure
when you touch the surface of a hologram.
Mobility Device
Honda has invented a personal mobility device--called U3-X--
that looks like a high-tech version of a unicycle. This device is
small and unobtrusive. It has tiny motor-controlled wheels
within one larger wheel that lets you glide in any direction. It
stands upright like a stool and travels approximately 3.7 miles per hour.

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Bacteria Drawings
Scientists are genetically engineering E.Coli bacteria to create
outlines of designed images. Their drawing creations include the
silhouetted face of filmmaker Alfred Hitchcock. They rely on the
bacteria's cells to detect light and dark, creating either black or
white pigments. 1 cell is considered 1 pixel. It takes about 12
hours for a picture to form.
Sound Blasters
Police departments have introduced long-range sound weapons
that can blast a three-mile radius from a particular spot. It has a
shrill warning sound that can reach a maximum of 151 decibels.
It can be as loud as a jet engine and is powerful enough for sound
damage to occur.
Photosynth 3-D Viewing
Innovations in Microsoft's photo-stitching technology lets you
to see models of cities through the use of thousands of
pictures, all compiled by an advanced algorithm. A digital
model of Rome can be executed with the help of 150,000
pictures taken by tourists and posted in Flickr. This algorithm
can match photos, zoom in on angles and use parallel
processing to achieve a 3-D model.
Driverless (Toy) Car
Robotics to the people - first offering is Anki Drive, a $200 racing
game in which toy cars can drive themselves. The cars carry
sensors that feed data to an iPhone or iPad, which players can
use to control speed and position for their cars. The Anki app
computes actions for the enemy cars so they can compete as
craftily as the humans.

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Target Following Autonomous Robot (TFAR)
- Saurav Saha, B.Tech. 2013
Build a cool robot which will follow you (or any other target) everywhere! That too using simple, readily
available parts. No prior programming knowledge or robotics experience necessary!
A signal source (an infra-red transmitter) is attached to the target and three signal sensors are attached to
the robot. Using these sensors, the robot determines the precise angle of the target (i.e. the transmitter) and
moves in that direction.
Step 1: Build the circuit

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Step 2: The Transmitter & Receiver
To make the target’s transmitter, any ordinary TV remote control can be used! You’ll just have to keep any
button pressed to make the robot follow you. (Optionally, you can make your own transmitter by building a
38 kHz IR modulation circuit using two 555 timers). The receiver is a TSOP1738 IC as shown in the circuit
diagram. It senses the 38 kHz IR signals emitted by the transmitter.
Step 3: Mechanical Construction
It’s very important to restrict the angle of reception for the 3 TSOP sensors. Black tape or a mechanical
housing can be used for the covering and slits should be made such that the following reception angles are
achieved: Front Sensor – 15 to 25˚, Left and Right Sensors – 180 ˚; refer to the coloured regions (blue, green
and red) shown in the bot diagram.
Step 4: Programming the Microcontroller
Download the program (hex file) from the GDrive link (given at the end of this article), and burn it on the
microcontroller (Atmega16), using a software like eXtreme Burner via an AVR programming cable. The
algorithm is very simple: it first scans the three sensors for a signal, and if the front sensor detects it, then it
moves forward. Otherwise, it rotates clockwise/anticlockwise corresponding to the right/left TSOP sensor.
And that’s it - a fully functional TFAR using minimal components! If you build it, you’ll notice one problem
though - it follows too well! , i.e. it will always hit the target and won’t know where to stop. To overcome this
problem and also add more features (like obstacle avoidance) don’t forget to read the next instalment in this
series: TFAR v2.0!
Visit this project’s Google Drive URL : http://goo.gl/iecZc (or scan the QR code on the left)
to download the program, circuit diagram, datasheets, and additional info.

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Touch Screens
- Sabarno Chowdhury, B.Tech. 2016
A touch screen is a display screen cum input device. It is a pressure sensitive device and is controlled by
simple or multi-touch gestures using finger(s) or stylus/light pen. A user interacts with the device by touching
pictures or words on the screen. The touchscreen enables the user to interact directly with what is displayed,
rather than using a mouse, touchpad, or any other intermediate device.
Touchscreens are common in devices such as game consoles, personal computers, tablet computers,
and smartphones. They can also be attached to computers or as terminals to networks. They also play a
prominent role in the design of digital appliances such as personal digital assistants (PDAs), satellite
navigation devices, mobile phones, and video games and some books (Electronic books).
Historically, the touchscreen sensor and its accompanying controller-based firmware have been made
available by a wide array of after-market system integrators, and not by display, chip, or motherboard
manufacturers. Display manufacturers and chip manufacturers worldwide have acknowledged the trend
toward acceptance of touchscreens as a highly desirable user interface component and have begun to
integrate touchscreens into the fundamental design of their products.
There are several principal ways to build a touchscreen. The key goals are to recognize one or more
fingers touching a display, to interpret the command that this represents, and to communicate the
command to the appropriate application.
In the most popular techniques, the capacitive or resistive approach, there are typically four layers:
 Top polyester coated with a transparent metallic conductive coating on the bottom
 Adhesive spacer
 Glass layer coated with a transparent metallic conductive coating on the top
 Adhesive layer on the backside of the glass for mounting.
When a user touches the surface, the system records the change in the electrical current that flows
through the display. In some touch screens, the piezoelectric effect is measured—the voltage
generated when mechanical force is applied to a material—that occurs chemically when a
strengthened glass substrate is touched.
In each case, the system determines the intended command based on the controls showing on the
screen at the time and the location of the touch.
There are a variety of touchscreen technologies that have different methods of sensing touch.
Resistive touch screens are the most widely used touch technology today. A resistive touch screen
monitor is composed of a glass panel and a film screen, each covered with a thin metallic layer,
separated by a narrow gap. When a user touches the screen, the two metallic layers make contact,
resulting in electrical flow. The point of contact is detected by this change in voltage.

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Infrared touch screen monitors do not overlay the display with an additional screen or screen
sandwich. Instead, infrared monitors use IR emitters and receivers to create an invisible grid of light
beams across the screen. This ensures the best possible image quality. When an object interrupts the
invisible infrared light beam, the sensors are able to locate the touch point.
SAW (Surface Acoustic Wave) touch screen monitors utilize a series of piezoelectric transducers and
receivers along the sides of the monitor’s glass plate to create an invisible grid of ultrasonic waves on
the surface. When the panel is touched, a portion of the wave is absorbed. This allows the receiving
transducer to locate the touch point and send this data to the computer. SAW monitors can be
activated by a finger, gloved hand, or soft-tip stylus. SAW monitors offer easy use and high visibility.
In optical touchscreens two or more image sensors are placed around the edges (mostly the corners)
of the screen. Infrared back lights are placed in the camera's field of view on the other side of the
screen. A touch shows up as a shadow and each pair of cameras can then be pinpointed to locate the
touch or even measure the size of the touching object. This technology is growing in popularity, due
to its scalability, versatility, and affordability, especially for bigger units.
Capacitive touch screens are the second most popular type of touch screens on the market. In a
capacitive touch screen monitor, a transparent electrode layer is placed on top of a glass panel, and
covered by a protective cover. When an exposed finger touches the monitor screen, it reacts to the
static electrical capacity of the human body; some of the electrical charge transfers from the screen
to the user. This decrease in capacitance is detected by sensors located at the four corners of the
screen, allowing the controller to determine the touch point. Capacitive touch screens can only be
activated by the touch of human skin or a stylus holding an electrical charge.
Touch screens have a wide variety of uses in today’s digital world. To name a few:-
 Mobiles & Laptops
 Informational Kiosks
 Restaurant systems
 Employee time clock
 Industrial & Domestic Automation systems
 Casino & other gaming systems
 Computer access for the differently abled
 Military gadgets
The wonder material Graphene is set to revolutionize the smartphone industry by replacing current
touchscreen technology, researchers have claimed. Currently, the majority of tablets and
smartphones are made using indium tin oxide, which is both expensive and inflexible. The second
might start to become apparent if the industry starts to produce bendable communications devices,

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perhaps in the form of smart watches which could clearly benefit from a bit of flexibility. Graphene is
considerably cheaper than the materials used in most modern smartphones and is suppler too.
Dr Alan Dalton of the University of Surrey led the investigation into the new material. Working
alongside researchers at the University of Dublin, he oversaw the production of hybrid electrodes, the
“building blocks of touchscreen technology”, using silver nanowires and graphene.
There is a cheaper and less environmentally harmful alternative, developed by MIT biochemist Dr
Angela Belcher and inspired by the multi-layered formation of abalone shells. It uses silver nanowires
scattered over a sheet of plastic.
The random structure of the nanowire also is harder to see than the regular patterns of other metal
meshes, and one does not have to match it up to the pixel pattern of the LCD to avoid a distracting
moiré effect. Moreover since the sensor is thinner, one does not get as much parallax distortion - what
one sees on screen is closer to where the pixels are physically placed, so one can touch things more
accurately.
Touch Screens reduce human efforts to a large extent because they require little thinking. They are a
form of direct manipulation that is easy to learn. Touch Screens are durable in public access and in
high volume usage. Today, a large share of population is computer literate, yet the touch screens have
been adopted by computer users of all abilities because it is simple, fast and innovative. In future there
would be no use of mouse and keyboard as they would be replaced by touch screens due to their
easier hand eye coordination than mice or keyboards.

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JavaScript-based Multiformat Sudoku Puzzle Solver
- Agomoni Sarkar and Sagar Dev Maity, B.Tech. 2015
Sudoku is a mathematical-cum-logical puzzle where every digit should come uniquely in every row and
column without repetition. We generally find Sudoku puzzles in dailies and magazines with various levels of
toughness with respect to placement of numbers, number of puzzle digits and blanks. Mostly, dailies publish
only numerical puzzles with limited matrix length of either 9×9 or 6×6. In this project, we show that non-
numeric entities can also be used to form a Sudoku grid. One can also define the size of the matrix beyond
6×6 and 9×9. In this project one can use numeric digits from 1-9, and alphabets in upper and lower cases (A-
Z, a-z).
Fig. 1: 6×6 matrix with non-numerics (unsolved and solved)
Fig. 2: 2×3 size, 6×6 matrix Fig. 3: 3×2 size, 6×6 matrix

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Fig. 4: 4×4 matrix with unsolved and solved puzzle
The 6×6 matrix with non-numerics is shown in Fig. 1. Likewise, one can have a one-cell grid of 1×1 size to
2401-celled grid of 7×7 size with the above characters. There are two programs for this project. The first code
is for solving the alphabet-based Sudoku puzzle and the later code is for numeric-based Sudoku puzzle.
In both case, the default size of the matrix is 3×3, which is a 9×9 matrix having 81-cell grids. User can change
the size from 1×1 up to 7×7 as per requirement.
The program is coded in JavaScript and when launched
using Internet Explorer, it displays a grid with predefined
numbers in each of the cells. The first cell represents the
rows, and the second cell represents columns. The rows
and columns of the cells define the size of the matrix.
Case 1: When ‘2’ is input in the first cell (column) and ‘3’
is input in the second cell (row), a 6×6 matrix with two
columns and three rows is generated, which is colour-
coded to differentiate between the distinct cell grids
(refer Fig. 2).
Case 2: When ‘3’ is input in the first cell (column) and ‘2’ is input in the second cell (row), a 6×6 matrix with
three columns and two rows is generated, which is colour-coded to differentiate between the distinct cell
grids (refer Fig. 3). One more characteristic feature of this program is its artificial intelligence type solving
ability that mimics human thinking in solving this puzzle. Please note that it does not use any fuzzy logic in
the backend but only JavaScript to attain this. Moreover, the program can only solve logically valid puzzles.
If more cells are filled in a puzzle, it takes less time to solve the puzzle, and vice-versa. It can generate either
symmetric or asymmetric puzzles, as per your requirement, i.e., it can generate 1×1, 9×9, or 1×2, 8×9 and
34×35 matrices or any other matrix up to 35×35. 4×4 matrix and 9×9 solved puzzles are shown in Figs 4 and
5, respectively.
Fig. 5: 9×9 matrix solved puzzle

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Crossword @ Electrovision
Across Down
1.Two resistors connected together, across a power
supply (9, 7)
2.Process used to remove unwanted copper from a
PCB (4)
3.Colour band used to indicate the number 7 (6)
4.Colour band used to indicate the number 0 (5)
5.Connects the components together on a PCB (5)
6.A component which allows current to flow only in
one direction (5)
7.Makes a sound (7)
8.A collection of components, connected together (7)
9.The L in LED (5)
10.Flows through a circuit (7)
11.Electronics that works with real voltages (9)
12.Type of capacitor, which is polarised (12)
1.Shape of the schematic symbol for a resistor (9)
2.Stores charge (9)
3.Electrically joints components to a PCB (6)
4.Energy that allows the electronics to work (5)
5.Check the board works, after construction (4)
6.A chip / part with two row of pins (10, 7)
7.Component with coloured bands to determine its
value (8)
8. Something that can only be true / false, 0 or 1 (7)
9.Used to turn things on and off (6)
10.Letters used to mark commercial electronics sold in
Europe (2)
11.Measured across components such as batteries (7)
12.A component that acts like an electronic switch (10)

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Did You Know? – An Electrical Plug Story
Electrical plugs and sockets differ in voltage and current rating, shape, size and type of connectors. The types
used in each country are set by national standards, some of which are listed in the IEC technical report TR
60083, Plugs and socket-outlets for domestic and similar general use standardized in member countries of
IEC. Plugs and sockets for portable appliances started becoming available in the 1880s, to replace connections
to light sockets with easier to use wall-mounted outlets. A proliferation of types developed to address the
issues of convenience and protection from electric shock. Today there are approximately 20 types in common
use around the world, and many obsolete socket types are still found in older buildings. Co-ordination of
technical standards has allowed some types of plugs to be used over wide regions to facilitate trade in
electrical appliances, and for the convenience of travellers and consumers of imported electrical goods. Some
multi-standard sockets allow use of several different types of plugs; improvised or unapproved adapters
between incompatible sockets and plugs may not provide the full safety and performance of an approved
socket and plug combination.

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Audio/Video Processors for Embedded Multimedia Designs
- Rajarshi Das, B.Tech. 2015
Over the last few years, we have seen a revolution in the field of entertainment devices. The list that began
with traditional radio and TV sets has exploded into an endless number of devices ranging from smartphones,
digital cameras and camcorders, portable media players, mobile Internet devices (MIDs), netbooks, all the
way up to large flat-panel displays, home theatre systems and much more.
Now, for most entertainment devices, processing audio and video is one of the most important functions,
and selecting an optimal processing solution is one of the keys to success for any product that has to do any
significant amount of computing. The desired product features influence the product cost, power
consumption and performance as well.
Aspects to be considered
Audio processors: Audio processors serve a variety of fields, and each of these fields has its own challenges
and design goals. In some fields, digital signal processing is used to produce high-fidelity sounds such as in
the entertainment industry where audio quality is paramount. On the other hand, communication systems
require the audio to be clear while keeping within a low data rate. While designing any audio processing
system, the designers have three primary targets to achieve: good audibility, intelligibility and fidelity.
Audibility: The audibility of speech or music must be sufficient to achieve the desired effect attained without
distortion or feedback.

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Intelligibility: Intelligibility is determined by the signal-to-noise ratio and direct-to-reverberant ratio at the
listener’s end. Whilst the system must suppress external as well as electrical noise produced within the
system itself, controlling the reverberation of acoustics produces good intelligibility.
Fidelity: Fidelity of sound is the overall frequency response of the sound, and a wide and relatively uniform
frequency range contributes to realistic and précise augmentation of sound. Fidelity is basically contributed
by every component, and any limitation at any point can affect the fidelity of the entire system.
Video processors: Video processing applications are growing exponentially, with the new kind of video-
centric products surfacing rapidly. Computationally demanding video processing has different requirements
for different applications. For instance, video applications such as home theatre systems require a processor
which is flexible enough to connect all components together, process the signal for a large living room,
creating an ultimate home theatre experience by delivering premium sound quality.
On the other hand, vehicle-reversing cameras and other small-screen LCD applications for both automotive
and non-automotive electronics require good image clarity. These applications also pose challenges such as
safety and reduced power consumption, especially in automotive systems in order to minimise the power
burden on the battery. This increasing range of applications poses a challenge for any designer who is
required to choose from so many processors and their complexities.
Let us take a look at what the audio/video processing industry has in offering for embedded multimedia
designs and development of feature-rich products.
Digital and analogue solutions: Analogue processors are used where we require the best quality output. T.
Anand, co-founder, Knewron explains, ”The thumb rule is, where the quality of audio/video is of prime
importance,we go for the analogue processing. The outputfrom an analogue IC is much better than a digitally
processed analogue output.” The latest analogue I²C-controlled audio processors offer a wide range of
features that are suitable for stereo and multichannel applications. These can save costs and enhance the
audio signal chain of the designs. Also, these devices with integrated features such as digital volume and
balance control, surround sound and tone controls, further enhance the designs.
These surround or other multichannel formats are appropriate for producing virtualised 3D sound for two-
speaker systems. Also, there are 3D audio processors which can create five-speaker surround sound from a

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two-channel stereo source. Although digital processing can be lossy, the advent of efficient and powerful
digital processors is an alternative to noise-prone analogue processing. Praveen Ganapathy, director,
Business Development, Texas Instruments, India says, “Anything in the real world is analogue, so traditionally
we could do processing in analogue domain; the only challenge is analogue domain is prone to a lot of noise.
So we take the inputs in analogue form and then convert them into digital, process in the digital domain and
then again convert to analogue form for the output. Digital audio processors offer more versatile handling of
audio/video streams. Echo cancellation and noise suppression DSP software technology is enhancing the
audio quality of wireless products while increasing versatility in multimedia application processor families is
allowing developers to design a wide range of end products with minimal incremental PCB design effort. Now
you can switch sample rates without changing coefficient and have more flexible designs with the new
simplified multichannel designs in digital audio processors.
Modernised system on chips (SoC) solutions: On one hand there is a wide range of fully integrated smart TV
SoCs, supporting full HD through the high resolution best suited for 3D graphics and 3D gaming. On the other
hand there are scalable processors with affordable ARM architecture solutions. These offer a broad range of
performance, price and power consumption to meet just about every need, and also include video
accelerators, advanced graphics and display capabilities and high-speed connectivity with a rich set of
peripherals that are optimised for a broad spectrum of digital video end equipment.
Consumer: SoCs with ARM architectures plus built-in hardware video accelerator engines are the solutions
for applications such as tablets and mobile phones. “The mobile phone budget cannot afford so many
dedicated chipsets for analogue-to-digital (A/D) conversion, codecs and for transmission. When you talk of
an SoC, it develops a balance between the cost, performance and power, providing the complete ecosystem
with the associated software at a good price that can fit into the mobile phone or a tablet,” says Avinash
Babu, senior architect, Mistral Solutions.
Automotive: For automotive multimedia designs which have been gaining popularity, the multi-tuner
RFCMOS single-chip solutions with embedded AM, FM and DAB tuners offer a combined car radio and audio
system fully integrated on a single IC. These can help you build the system with significantly reduced system
costs via a reduced bill of material (BOM). Time to market is also a very important factor for the designers.
Gaurav Kapoor, sales manager, Intersil Corp, India, says, “There are simple low-cost controllers that help
designers to kick start design and time to market, as there are no software protocols required since these
devices can run by setting the simple register mapping.” These controllers can be best suited for simple
automotive safety applications such as rear-view camera display where, instead of having complex software-
based controllers for the interaction with the display devices, you can use these dedicated LCD controllers
for straight connection with digital LCD panel. You can thus make the solution ready within a couple of weeks
and production ready within a few months because of simpler designing.
Critical applications: Talking about surveillance and portable processing needs for weapon-mounted sights,
handheld range and target finders, and unmanned air or ground platforms, the module should first meet the

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demanding size, weight and power constraints. The combination of dedicated image-processing cores and
an abundance of peripherals in a single integrated circuit has resulted in all-in-one image processors with a
general-purpose computer. These can be useful for performing other critical non-vision tasks, such as flight
control and system-to-system communication. The optimised real-time vision-processing hardware performs
operations such as noise reduction, image enhancement, image fusion, stabilisation and object tracking.
HDMI transceivers: These transceivers have evolved offering flexibility for your designs. These allow you to
separate the audio from video or vice versa. Such transceivers let the video pass through and bring out a
compressed audio on the device for DSP to process. A good thing about such devices is that these are not
only useful for home audio and video but also for professional AVs. Subramanyam of Analog Devices, India
says, “You can take the audio out from these transceivers and reinsert it back, which is a kind of requirement
for studio equipment. It offers a kind of great flexibility, taking audio from one channel and putting audio and
video on different locations.”
Smart amplifiers: An amplifier is an integral part of an audio system. Digital amplifier products, where
analogue quality performance, reduced size and improved energy efficiency are at premium, have been the
focus of the market in recent times. As a result, the ‘smart’ amplifiers have surfaced for helping the design
engineers. These smart amplifiers amplify the signal with constant monitoring of the functional device,
thereby protecting it from damage and at the same time ensuring the quality of the output.
Ganapathy explains, “The smart amplifier technology allows you to have a 5W speaker with 10x the range
without damaging the speakers, so with 5W you can have the 50W experience and thus have more compact
designs. It continuously monitors speaker characteristics and responds accordingly; this is how you get good
audio tones without damaging the speakers.”
Over the years use of smart devices has become common, but the potential interference they generate has
always retarded the aim of providing an excellent sound performance. The new amplifiers that have come
up for the smart devices, provide increased GSM robustness to mitigate the influence of smartphones on
loudspeakers, resulting in a cost-effective solution that improves sound quality.
IDEs for better designing: In the recent times, IDE software with feature-rich GUI for the embedded
processor families has been the focus of many leading chip vendors. These employ the latest generation of
mature code-generation tools and provide seamless, intuitive C/C++ and Assembly language editing, code-
gen and debug supports, thereby making processor selection and product design more engineer friendly.
Subramanyam says, “Historically what used to happen was, if you were to create a sound bar or an AVR, you
would tend to have the audio engineer and the software engineer sit together and try to choose the product.
but in this case the graphical user interface offered for these DSPs enables the audio engineer to change the
characteristics of various builders or the crossovers.” Additionally, the advanced algorithms for video
processing have evolved for noise reduction as well as image formatting and conversion. The image
enhancement algorithms add details to low-resolution images and adjust colour and contrast giving crisp,
clear images on your display. These advanced algorithms and encodings are reducing the computations,

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thereby reducing the power consumptions as well. Babusays, “On the way, people are trying to reduce power
consumptions using accelerators, which are built using higher silicon technologies, and reducing the amount
of data payload through advanced encodings.”
Energy consumption: Managing the energy consumption is a major challenge for the application design
technology today. Subramanyam says, “Energy consumption is a very important aspect of the consumer
electronics industry today. the reason being, when you are watching the TV and you put it on standby, or if
you put your audio system on standby, you would like the standby power of these devices to be very low.
Most of the DSPs that we design have a full operational mode and then a standby mode. The standby mode
helps in saving power.”
“We have ICs ranging from a few nanoamperes to a few milliamperes—it differs from product to product.
and the market is pretty sensitive to the products which have sleep modes, hibernation modes, etc,” he adds.
Other modules: We all know how important are analogue-to-digital converters (ADCs) and digital-to-
analogue converters (DACs) for any signal processing system. These become essential while processing
analogue signals such as voice or speech, and are used for enhancing voice processing features such as noise
suppression, acoustic echo cancellation and multichannel beamforming. They also offer improved
performance in voice capture processing such as voice control and recognition. other applications such as
digital set-top box systems, digital video camcorders, smartphones and tablets operating with digital signals
are also designed with reliable, low-power and high-performance ADCs.
We have single packages for sampling, A/D conversion and anti-alias filtering, generating 24-bit values for
both left and right inputs in serial form at sample rates up to 200kHz per channel. Most of the packages
employ fifth-order, multi-bit delta sigma modulator followed by digital filtering and decimation, which
removes the need for an external anti-alias filter, thereby reducing the number of components required for
the designs. Further, audio/video codecs which combine audio ADCs and DACs into single ICs provide
maximum flexibility, features and performance in the multimedia designs.
The risk factor: Ever-growing and highly-demanding entertainment and multimedia industry poses some
risks as well for your designs. The primary one being the reliability and your commitment to future evolutions
of the design. Although multi-vendor architecture is a plus point for the designs but a roadmap for the next-
generation architectures and compatibility with the future parts will ensure improved integrations and
reduced costs for your designs. Nate Srinath, founder and director, Inxee says, “Every designer should try to
mitigate business risk by adopting a multi-vendor capable architecture. The selection process should consider
every A/V processor vendor’s commitment and roadmap, coupled with technical and reference design
support, along with proper software tools to mitigate business risk during developmental stages of the
product.”

22
Where Do Open Source Engineers Fit in the Electronics Industry
- Roopam Das, B.Tech. 2013
It has been believed for years that a prominent part of the future of Open Source lays in embedded systems—
a “rather unglamorous child of the computer world,” as Linus Torvalds states. According to Linux Adoption
Trends 2012, a study released by The Linux Foundation, Linux continues to see strong gains in the enterprise
market.
Open Source electronics is considered a promising career path today as new digital devices are invented
every now and then. Soon Open Source hardware will witness the sort of technology innovation that Open
Source software kicked off a decade ago.
“We have noticed an increasing demand for electronics engineers who are experienced in Open Source
technologies, mainly due to the change in development towards a more social and collaborative
development framework. Organisations are recognising the value of Open Source in reducing time and cost
by not reinventing the wheel,” reveals Francis Kwang, APAC pre-sales manager of Acronis—an organisation
that provides data backup software and disaster recovery solutions.
Open Source hardware is any hardware with its design made publicly available. It allows anyone to study,
modify, distribute, and make or sell the new design or hardware. Hardware design, including schematics, bill
of materials and PCB layout data, and the software that drives the hardware are all released with the Open
Source approach. Ideally, Open Source hardware freely gives information about how it was created and uses
readily-available components and materials, standard processes, open infrastructure, unrestricted content,
and Open Source design tools to maximise the ability of individuals to make and use hardware. It gives people
the freedom to control their technology while sharing knowledge and encouraging commerce through open
exchange of designs.
How Open Source fits into electronics
One of the main areas where Open Source plays a major role is device drivers.
“A device driver can be written either by a computer software engineer or an electronics engineer,” says
Divyanshu Verma, engineering manager, Dell India R&D.
“However, a software professional often knows more about the database and algorithms than how a chip
works. In this area, an electronics engineer scores over a software engineer. Those who understand ‘C’ and
Assembly languages and have the basic understanding of operating systems can understand how to write a
device driver,” he adds.
Electronics engineers are also required in the Open Source embedded systems domain in areas such as board
design and integration programming. Microcontrollers and control programming is exclusively an electronics
engineer’s domain. Data acquisition systems or control systems with real-time operating systems also require
the hands of an electronics engineer. Only an electronics engineer is equipped to understand how data

23
travels from one digital system to another. A non-programming area where electronics engineers get
involved is board design.
“DSP chips is another area where electronics engineers can play a significant role, as they have an added
advantage over software engineers in writing software algorithms for hardware codecs,” Verma adds.
These jobs require device driver and hardware related knowledge, and a good understanding of the system
on chip. The programming language is ‘C’ and Assembly. Electronics engineers play a very important role in
the development of embedded systems, network switching and handheld devices. They can take
entrepreneurial path too using Open Source.
Build your Open Source skills
Open Source electronics is not a common topic found in university syllabi. Instead, most people refer to
resources on the Internet. Luke Soules, the founder of ifixit.com, feels that those without hardware
knowledge can easily get started with electronics and those who have not programmed before can
experiment on boards with Open Source projects.
“The best example of a successful Open Source hardware project is Arduino. It is a microcontroller platform
with digital input and output, and analogue input and output that lets you build things,” Soules stated in a
panel discussion titled ‘The Rise of Profitable Open Source Hardware’ available online.
Arduino is an Open Source electronics prototyping platform based on flexible, easy-to-use hardware and
software. It is intended for artists, designers, hobbyists and anyone interested in creating interactive objects
or environments. Arduino can sense the environment by
receiving input from a variety of sensors and affect its
surroundings by controlling lights, motors and other
actuators. The microcontroller on the board is programmed
using the Arduino programming language based on Wiring
and the Arduino development environment based on
Processing. Arduino projects can be standalone or they can
communicate with the software on running on a computer
(Processing, MATLAB and MAX/MSP). Vinay Chaddha, an innovator and embedded software and hardware
developer, feels most colleges don’t teach Open Source electronics due to lack of awareness. In such a
situation, reading electronics periodicals and blogs can help in understanding electronics.
Chaddha says, “Open Source electronics is simple, everyday electronics. The only addition is that all the
information is available in public domain and there are many people working on it. So there is a large
community and support is easy. Also, you do not have to start from scratch.”
He recommends that doing internships and experimenting is much more beneficial than undergoing paid
training. A good way to start is exploring community projects, and working and tweaking existing device
drivers that are a part of Open Source community.

24
“You can buy one of the boards such as Beagleboard (which costs around $100), use the supporting material
that is available on the website and build your own applications. Hands-on implementation is the key to
learning. We tend to look for a strong embedded systems background with good knowledge of Linux and ‘C’
as the candidates have to handle product application and development,” reveals Giri Krishna, CEO of Silvan
Innovation Labs.
Krishna adds, “We work with the development boards and kits provided by vendors to develop our own
applications. For example, we have used the Leopard board to develop IP surveillance cameras.”
Meanwhile, Kwang feels that Open Source does not present any barrier to entry. “One’s willingness to
embrace Open Source and a keen eye for opportunities, changes and demands are the most important
factors. Linux is fundamentally a great place to start. SourceForge.com is another excellent starting spot.
Some of the tasks performed by an electronics engineer at Acronis are customisation, integration, and
managing the interoperability of Open Source tools and codes,” he adds.
Verma recommends online self-learning. “Those who want to learn about Open Source hardware can join
Openhardware.org—an initiative to Open Source hardware. It consists of physical artefacts of technology
designed and offered in the same manner as free and Open Source software. A candidate can also opt for
renowned certifications such as CDAC—a course that takes six to nine months to complete. However, as
candidates learn the subject, they must acquire a strong understanding of hardware and its working, digital
electronics fundamentals, systems domain and operating systems. The skills we look for are a good
understanding of computer architecture, knowledge of ‘C’ and Assembly languages, problem solving and
debugging skills, and knowledge of microprocessors and microcontrollers. All semiconductor and real-time
system development companies recruit Open Source electronics engineers,” Verma shares.
Will open hardware rival open software in popularity?
An increasing number of start-ups and entrepreneurial initiatives are opting for Linux in embedded systems
for handheld devices, network switches, etc. There is a lot of focus on low-power architecture these days,
where electronics engineers can play a crucial role. In software, the demand for people experienced in Open
Source has increased as organisations get a deep understanding and foundation of software.
Then asked whether we will see a similar trend in electronics engineers who have worked on Open Source,
Verma replied, “Yes, it is very true for electrical engineers who have a very good understanding of hardware.
They can be very helpful in designing real-time systems,human-machine interfaces, data acquisition systems,
point-of-sale devices, etc.” Krishna believes that some companies are trying the route of Open Source
electronics to enable people to develop products, but have not reached the same level of popularity as is
seen with software. “Open Source electronics is still in a very nascent stage. The entire industry might have
to wait for a few more years before it becomes a significant movement that leads to job creation in large
numbers. One example I have closely observed is Texas Instruments which has deployed low-cost
development boards based on its OMAP and Da Vinci product lines. They have also provided development
kits with the boards to enable easy application development,” he adds.

Photo Gallery
HOD at IEMCON 2013 delivering keynote address
Talk by TCS
25

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Gadget Speak
- Binayak Chandra, B.Tech. 2015
A New King – S IV v/s Sony Xperia Z v/s HTC One
A new year, a new Galaxy. Samsung has finally unveiled the successor to their best selling Galaxy S3 Android
smartphone, and while not carrying a fancy new face like the trend with the past three flagships, Samsung
has gone the Apple way by making subtle design changes instead, and focusing more on the core experience
with its software customization. 2 years ago, who would have thought any other company would follow in
the footsteps of Apple (albeit in a different style), yet here they are, Samsung at the top of the world’s
smartphone manufacturers. Borrowing heavily from the previous flagship, the Galaxy S IV is a familiar face
with refreshed specifications that make it ready enough to take on the heavy weights that will be released
throughout 2013 (or for most of it). The Galaxy S IV will come in two distinct flavours, one donning the
Samsung made Exynos 5 Octa chipset, while some regions will receive the new Qualcomm Snapdragon 600
chipset.
It was always known that the Galaxy S IV would be a big scorer in benchmarks. However, I had reserved those
thoughts for the Exynos 5 Octa chipset. However, it seems that Samsung won’t let its 4G capable Snapdragon
600 chipset based variant lower the overalls, with the Galaxy S IV scoring high enough to beat out old
champions such as the Galaxy S3, iPhone 5 and even the newly introduced HTC One (which is also based on

29
a Snapdragon 600 chipset). It’s real nice to see that the Snapdragon 600 based Galaxy S IV will also be a
benchmark (and otherwise) monster of a phone.
HP Envy Series of Laptops
HP originally launched the line on October 15, 2009 with two high performance models, the Envy 13 and the
Envy 15. These models replaced the Voodoo Envy when HP and VoodooPC merged. After that, HP expanded
the series with the addition of the Envy 14 and Envy 17 models. In 2012, HP discontinued their traditional
Envy 13, 14, 15 and 17 models by rebranding their Pavilion line of computers as the new Envy lineup. The
new ENVY line has a starting price of $499 USD, and consists of the (rebranded Pavilion) Envy notebook line
and the hybrid HP Envy x2. The rebranded Pavilion laptops continue with Beats Audio branded speakers and
dedicated NVIDIA graphic processors.
There are three Ultrabooks in the early 2013 ENVY lineup - the ENVY 4 TouchSmart, ENVY 4, and ENVY 6.
Envy X2
The HP ENVY X2 is a tablet with a removable keyboard dock.
Envy Dv6
The Envy Dv6 is a 15.6-inch laptop starting at ~$700-1300 USD that resembles the previous Pavilion Dv6. It
weighs ~5 pounds and can be customized to accommodate a 1080p TN matte display, multi-touch trackpad,
and up to 1.5TB HDD. The HP Envy Dv6 runs Windows 8 and is replacement to the successful HP Envy 15. The
Dv6 can be configured to have an Intel Core i7 Mobile processor, Up to NVIDIA GT650M graphics and a backlit
keyboard. The Dv6 comes with beats audio and has a mostly aluminum chassis. There are two main variants
of the Dv6, the Dv6 comes with AMD processors while the Dv6t come with Intel processors.
Envy Dv7
The Envy Dv7 is a high-end 17.3-inch laptop priced at ~$800–1600 USD (depending on the configuration) that
resembles the previous Pavilion Dv7. It weighs ~6 pounds and can
be customized to accommodate a 1080p TN matte display, multi-
touch track-pad, and can hold two hard drives (Up to 1 TB each
when bought from HP ). The HP Envy Dv7 runs Windows 8 and is
replacement to the successful HP Envy 17. The Dv7 can be
configured to have an Intel Core i7 Mobile processor, Up to
NVIDIA GT650M graphics and a backlit keyboard. The Dv7 comes
with Beats Audio and has an aluminium chassis. There are two main variants of the Dv7; the Dv7z has AMD
processors while the Dv7t come with more powerful Intel processors.
User review HP ENVY X2 turns out to be a dream come true for me. It’s the first of its kind, a hybrid between
laptops and palmtops. Its detachable keyboard dock makes it a stunner with techies. Take it from me folks,
if you are looking for a blend of innovation and technology, nothing will suit you better than ENVY 2. Showing
off in front of buddies or impressing or girlfriend is easy if you have one of these in hand.

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Biochips
- Mustafizur Ali, B.Tech. 2016
Most of us won’t like the idea of implanting a biochip in our body that identifies us uniquely and can be used
to track our location. That would be a major loss of privacy. But there is a flip side to this! Such biochips could
help agencies to locate lost children, downed soldiers and wandering Alzheimer’s patients.
The human body is the next big target of chipmakers. It won’t be long before biochip implants will come to the
rescue of sick, or those who are handicapped in someway. Large amount of money and research has already
gone into this area of technology.
Anyway, such implants have already experimented with. A few US companies are selling both chips and their
detectors. The chips are of size of an uncooked grain of rice, small enough to be injected under the skin using
a syringe needle. They respond to a signal from the detector, held just a few feet away, by transmitting an
identification number. This number is then compared with the database listings of register pets.
Daniel Man, a plastic surgeon in private practice in Florida, holds the patent on a more powerful device: a chip
that would enable lost humans to be tracked by satellite.
A biochip is a collection of miniaturized test sites (microarrays) arranged on a solid substrate that permits many
tests to be performed at the same time in order to get higher throughput and speed. Typically, a biochip’s
surface area is not longer than a fingernail. Like a computer chip that can perform millions of mathematical
operation in one second, a biochip can perform thousands of biological operations, such as decoding genes, in
a few seconds.
A genetic biochip is designed to “freeze” into place the structures of many short strands of DNA
(deoxyribonucleic acid), the basic chemical instruction that determines the characteristics of an organism.
Effectively, it is used as a kind of “test tube” for real chemical samples.
A specifically designed microscope can determine where the sample hybridized with DNA strands in the
biochip. Biochips helped to dramatically increase the speed of the identification of the estimated 80,000 genes
in human DNA, in the world wide research collaboration known as the Human Genome Project. The microchip
is described as a sort of “word search” function that can quickly sequence DNA.
In addition to genetic applications, the biochip is being used in toxicological, protein, and biochemical research.
Biochips can also be used to rapidly detect chemical agents used in biological warfare so that defensive
measures can be taken. Motorola, Hitachi, IBM, Texas Instruments have entered into the biochip business.
The biochip implants system consists of two components: a transponder and a reader or scanner. The
transponder is the actual biochip implant. The biochip system is radio frequency identification (RFID) system,
using low-frequency radio signals to communicate between the biochip and reader. The reading range or
activation range, between reader and biochip is small, normally between 2 and 12 inches.

31
The transponder is the actual biochip implant. It is a passive transponder, meaning it contains no battery or
energy of its own. In comparison, an active transponder would provide its own energy source, normally a small
battery. Because the passive contains no battery, or nothing to wear out, it has a very long life up to 99 years,
and no maintenance. Being passive, it is inactive until the reader activates it by sending it a low-power electrical
charge. The reader reads or scans the implanted biochip and receives back data (in this case an identification
number) from the biochips. The communication between biochip and reader is via low-frequency radio waves.
Since the communication is via very low frequency radio waves it is not at all harmful to the human body.
The biochip-transponder consists of four parts; computer microchip, antenna coil, capacitor and the glass
capsule.
The microchip stores a unique identification number from 10 to 15 digits long. The storage capacity of the
current microchips is limited, capable of storing only a single ID number. AVID (American Veterinary
Identification Devices), claims their chips, using a nnn-nnn-nnn format, has the capability of over 70 trillion
unique numbers. The unique ID number is “etched” or encoded via a laser onto the surface of the microchip
before assembly. Once the number is encoded it is impossible to alter. The microchip also contains the
electronic circuitry necessary to transmit the ID number to the “reader”.
Biochip & Syringe

32
Antenna Coil is normally a simple, coil of copper wire around a ferrite or iron core. This tiny, primitive, radio
antenna receives and sends signals from the reader or scanner.
The tuning capacitor stores the small electrical charge (less than 1/1000 of a watt) sent by the reader or
scanner, which activates the transponder. This “activation” allows the transponder to send back the ID number
encoded in the computer chip. Because “radio waves” are utilized to communicate between the transponder
and reader, the capacitor is tuned to the same frequency as the reader.
The glass capsule “houses” the microchip, antenna coil and capacitor. It is a small capsule, the smallest
measuring 11 mm in length and 2 mm in diameter, about the size of an uncooked grain of rice. The capsule is
made of biocompatible material such as soda lime glass.
After assembly, the capsule is hermetically (air-tight) sealed, so no bodily fluids can touch the electronics inside.
Because the glass is very smooth and susceptible to movement, a material such as a polypropylene polymer
sheath is attached to one end of the capsule. This sheath provides a compatible surface which the boldly tissue
fibers bond or interconnect, resulting in a permanent placement of the biochip.
The biochip is inserted into the subject with a hypodermic syringe. Injection is safe and simple, comparable to
common vaccines. Anesthesia is not required nor recommended. In dogs and cats, the biochip is usually
injected behind the neck between the shoulder blades.
The reader consists of an “exciter coil” which creates an electromagnetic field that, via radio signals, provides
the necessary energy (less than 1/1000 of a watt) to “excite” or “activate” the implanted biochip. The reader
also carries a receiving coil that receives the transmitted code or ID number sent back from the “activated”
implanted biochip. This all takes place very fast, in milliseconds. The reader also contains the software and
components to decode the received code and display the result in an LCD display. The reader can include a RS-
232 port to attach a computer.
Process of Work: The reader generates a low-power, electromagnetic field, in this case via radio signals, which
“activates” the implanted biochip. This “activation” enables the biochip to send the ID code back to the reader

33
via radio signals. The reader amplifies the received code, converts it to digital format, decodes and displays the
ID number on the reader’s LCD display. The reader must normally be between 2 and 12 inches near the biochip
to communicate. The reader and biochip can communicate through most materials, except metal.
Biochips Currently Under Development
1. Chips that follow footsteps
2. Glucose level detectors
3. Oxy sensors
4. Brain surgery with an on-off switch
5. Adding sound to life
6. Experiments with lost sight
The civil liberties debate over biochips has obscured their more ethically benign and medically useful
applications. Medical researchers have been working to integrate chips and people for many years, often
plucking devices from well known electronic appliances. Jeffry Hausdorff of the Beth Israel Deaconess Medical
Center in Boston has used the type of pressure sensitive resistors found in the buttons of a microwave oven as
stride timers. He places one sensor in the heel of a shoe, and one in the toe, adds a computer to the ankle to
calculate the duration of each stride.
“Young, healthy subjects can regulate the duration of each step very accurately,” he says. But elderly patients
prone to frequent falls have extremely variable stride times, a flag that could indicate the need for more
strengthening exercises or a change in medication. Hausdorff is also using the system to determine the success
of a treatment for congestive heart failure. By monitoring the number of strides that a person takes, can directly
measure the patient’s activity level, bypassing the often-flowed estimate made by the patient.
S4MS is still developing the perfect fluorescent chemical, but the key design innovation of the S4MS chip has
been fully worked out. The idea is simple: the LED is sitting in a sea of fluorescent molecules. In most detectors
the light source is far away from the fluorescent molecules, and the inefficiencies that come with that mean
more power and larger devices. The prototype S4MS chip uses a 22 microwatt LED, almost forty times less
powerful than a tiny power-on buttons on a computer keyboard. The low power requirements mean that
energy can be supplied from outside, by a process called
induction. The fluorescent detection itself does not
consume any chemicals or proteins, so the device is self
sustaining.

34
The S4MS Chip Sensing Oxygen or Glucose
Drug therapy of Parkinson’s disease aims to replace the brain messenger dopamine, a product of brain cells
that are dying. But eventually the drug’s effects wear off, and the erratic movements come charging back.
The Activa implant is a new alternative that uses high-frequency electric pulses to reversibly shut off the
thalamus. The implantation surgery is far less traumatic than thalamatomy, and if there are any post-operative
problems the stimulator can simply be turned off. The implant primarily interferes with aberrant brain
functioning. The most ambitious bioengineers are today trying to add back brain functions, restoring sight and
sound where there was darkness and silence. The success story in this field is the cochlear implant. Most
hearing aids are glorified amplifiers, but the cochlear implant is for patients who have lost the hair cells that
detect sound waves. For these patients no amount of amplification is enough.
The Clarion Cochlear Implant
OPTICAL
FILTER
PHOTODIODE DETECTOR
FLUORESCENT
MOLECULES
LED

35
The cochlear implant delivers electrical pulses directly to the nerve cells in the cochlea, the spiral-shaped
structure that translates sound in to nerve pulses.
In normal hearing individuals, sound waves set up vibrations in the walls of the cochlea, and hair cells detect
these vibrations. High-frequency notes vibrate nearer the base of cochlea, while low frequency notes nearer
the top of the spiral. The implant mimics the job of the hair cells. It splits the incoming noises into a number of
channels (typically eight) and then stimulates the appropriate part of the cochlea.
The two most successful cochlear implants are ‘Clarion’ and ‘Nucleus’.
Within ten years you will have a biochip implanted in your head consisting of financial status, employment and
medical records. Even in a grocery store, sensor will read the credit chip and will automatically debit the
account for purchase. A biochip implanted in our body can serve as a combination of credit card, passport,
driver’s license and personal diary. And there is nothing to worry about losing them.
ANSWER
TO
CROSSWORD:

36
Website Design
- Archisman Saha, B.Tech. 2016
Websites are very important tool for representing the data online in a very attractive format in which the
data can be shared among distant people.
› A webpage is a single HTML document
› A website is a collection of related webpages
Designing a good website requires more than just putting together a few pages.
Types of Web Pages
1. Static (abstract) web pages- A static page with no interaction that user will only read and close if.
2. Dynamic (proactive) web pages- A dynamic page that will take user name and password and check
it to allow login.
Server Architecture
Server-Side Dynamic Web Programming
CGI is one of the most common approaches to server-side programming.
Universal support: Almost every server supports CGI programming. A great deal of ready-to-use CGI code.
Most APIs (Application Programming Interfaces) also allow CGI programming.
Choice of languages: CGI is extremely general, so that programs may be written in nearly any language. Perl
is by far the most popular, with the result that many people think that CGI means Perl. But C, C++, Ruby, and
Python are also used for CGI programming.
Drawbacks: A separate process is run every time the script is requested. A distinction is made between HTML
pages and code. Other server-side alternatives try to avoid the drawbacks
User
Profile
web serverweb serverWeb Server
Scripts
LoadBalancer
Ad
Server
Web
Services
Apache

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Server-Side Includes (SSI): Code is embedded in HTML pages, and evaluated on the server while the pages
are being served. Add dynamically generated content to an existing HTML page, without having to serve the
entire page via a CGI program.
Active Server Pages (ASP, Microsoft) : The ASP engine is integrated into the web server so it does not require
an additional process. It allows programmers to mix code within HTML pages instead of writing separate
programs. (Must be run on a server using Microsoft server software.)
Java Servlets (Sun): As CGI scripts, they are code that creates documents. These must be compiled as classes
which are dynamically loaded by the web server when they are run.
Java Server Pages (JSP): Like ASP, another technology that allows developers to embed Java in web pages.
Web Development Languages & Tools
1. HTML/DHTML/XHTML
2. Java
3. Web Design Tools e.g. Frontpage, Dreamweaver.
3. Scripting Languages e.g. VBScript, Javascript
4. Cascading Style Sheets
5. XML, and …more!!!
You do not have the layout control in a web editor that you do in Word or PowerPoint.
Therefore, the web designers used tables to control the layout out of their pages. If you set the borders of
the table to 0 width, you can't see the outline of the tables in the web browser.
HTML
• Hyper Text Markup Language
• Developed by Tim Berners lee in 1990.
• An extended version of SGML.
• Easy to use ,Easy to learn
• Markup tags tell the browser how to display the
page.
• A HTML file must have an extension .htm or.html.
• HTML tags are surrounded by “<“and“>” (angular
brackets).
• Tags normally come in pairs like <H1> and </H1>.
• Tags are not case sensitive i.e. <p> is same as <P>.
• The first tag in a pair is the start tag, the second
tag is the end tag.
• Empty tags & non-empty tags.

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MySQL
• MySQL is the most popular open source database server.
• A database defines a structure for storing information.
• With MySQL, we can query a database for specific information and have a recordset
returned.
• MySQL is ideal for both small and large applications
• MySQL supports standard SQL
• MySQL compiles on a number of platforms
• MySQL is free to download and use
• PHP combined with MySQL are cross-platform (means that you can develop in Windows and
serve on a Unix platform)
• MySQL is a relational database system.
• It can store bits of information in separate tables and link those tables together.
• Each table consists of separate fields, which represent each bit of information.
PHP
PHP is a server-side scripting language designed for web development but also used as a general-purpose
programming language. As of January 2013, PHP was installed on more than 240 million websites (39% of
those sampled) and 2.1 million web servers. Originally created by Rasmus Lerdorf in 1994, the reference
implementation of PHP (powered by the Zend Engine) is now produced by The PHP Group. While PHP
originally stood for Personal Home Page, it now stands for PHP: Hypertext Preprocessor, which is a recursive
backronym.
Rasmus Lerdorf, who wrote the original Common Gateway Interface (CGI) component, together with Andi
Gutmans and Zeev Suraski, who rewrote the parser that formed PHP 3. PHP received mixed reviews due to
lacking native Unicode support at the core language level. In 2005, a project headed by Andrei Zmievski was

39
initiated to bring native Unicode support throughout PHP, by embedding the International Components for
Unicode (ICU) library, and representing text strings as UTF-16 internally.
• PHP (Hypertext Preprocessor)
• PHP is a server-side scripting language designed for web development but also used as a
general-purpose programming language. As of January 2013, PHP was installed on more than
240 million websites (39% of those sampled) and 2.1 million web servers.
• Simple and powerful SSSL
• Dynamic web pages.
• It’s like ASP.
• PHP scripts are executed on the server .
• PHP files have a file extension of ".php", ".php3", or ".phtml".
JavaScript
• JavaScript ≠ Java
• Developed by Netscape
• Purpose: to Create Dynamic websites
• Starts with < script type=“text/java script”> and ends with < /script>.
• Easy to learn, easy to use.
• More powerful, loosely typed
• Conversion automatically
• Used to customize web pages.
• Make pages more dynamic.
• To validate CGI forms.
• It’s limited (cannot develop standalone applications)
• Widely Used
WAMP
• W :- Windows XP/Vista
• A :- Apache version 2.2.6
• M :- MySQL version 5.0.45
• P :- PHP version 5.2.5

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Internet of Things
- Paresh Prakhar, B.Tech. 2016
Technology pioneer Kevin Ashton coined the term at a presentation given to Procter & Gamble in 1999. A
decade later he used the term again in a RFID Journal article, titled ‘That ‘Internet of Things’ Thing’.
If early versions of the internet were about data created by people, the next version is all about data created
by things. The Internet of Things (IoT) refers to everyday appliances and gadgets (‘things’) such as televisions,
medical devices and cars connected to the internet via tiny machine-readable radio frequency identifier
(RFID) tags. The RFID tags enable devices to automatically transfer data over a network without requiring
human-to-human or human-to-computer interaction. Although variations have sprung up since, including
M2M (machine-to-machine) and Cisco’s Internet of Everything, it’s the original term that has passed into the
general lexicon. The IoT now encompasses pretty much any device with embedded technology – from RFID
through to sensor-based computing and QR codes – that allows the device to interact with other devices and
the environment.
Not surprisingly, given its ever-expanding definition, the term Internet of Things has been branded as
inaccurate. In reality, ‘things’ don’t have their own internet; they use the regular internet. There is no
separate ‘Internet of Things’. ‘Things of the internet’ would be closer to the truth – but who wants that
mouthful? To further complicate matters, the ability to connect to the internet is not a prerequisite for
devices to be considered part of the IoT. Some can connect peer-to-peer, or over a local network, without
going online. Butlet’s not get too technical … What is undeniable is this: the IoT has the potential to transform
daily life for both consumers and businesses. For instance, food retailers may no longer run out of stock or
generate waste products, as everyone in the supply chain would know which products have been consumed
and need restocking. Likewise, manufacturing equipment can issue a warning before it malfunctions.
On the consumer front, start-ups and manufacturers have already introduced web-connected products with
smartphone apps or access to social networks. One example everyone seems to love is the smart fridge,
which keeps track of food usage and will notify you when stocks are low. The IoT takes the concept of
ubiquitous technology, such as Google Glass, and extends it to every home, car, business, building and system
in the world. The IoT can find its applications in almost every aspect of our daily life:
1) Prediction of natural disasters: The combination of sensors and their autonomous coordination and
simulation will help to predict the occurrence of land-slides or other natural disasters and to take appropriate
actions in advance.
2) Industry applications: The IoT can find applications in industry e.g., managing a fleet of cars for an
organization. The IoT helps to monitor their environmental performance and process the data to determine
and pick the one that need maintenance.

41
3) Water Scarcity monitoring: The IoT can help to detect the water scarcity at different places. The networks
of sensors, tied together with the relevant simulation activities might not only monitor long term water
interventions such as catchment area management, but may even be used to alert users of a stream, for
instance, if an upstream event, such as the accidental release of sewage into the stream, might have
dangerous implications.
4) Design of smart homes: The IoT can help in the design of smart homes e.g., energy consumption
management, interaction with appliances, detecting emergencies, home safety and finding things easily,
home security etc.
5) Medical applications: The IoT can also find applications in medical sector for saving lives or improving the
quality of life e.g., monitoring health parameters, monitoring activities, support for independent living,
monitoring medicines intake etc.
6) Intelligent transport system design: The Intelligent transportation system will provide efficient
transportation control and management using advanced technology of sensors, information and network.
The intelligent transportation can have many interesting features such as non-stop electronic highway toll,
transportation law enforcement, vehicle rules violation monitoring, reducing environmental pollution etc.
Challenges:
1) Naming and Identity Management: The IoT will connect billions of objects to provide innovative services.
Each object/sensor needs to have a unique identity over the Internet. Thus, an efficient naming and identity
management system is required that can dynamically assign and manage unique identity for such a large
number of objects.
2) Interoperability and Standardization: Many manufacturers provide devices using their own technologies
and services that may not be accessible by others.
3) Information Privacy: The IoT uses different kind of object identification technologies e.g., RFID, 2D-
barcodes etc. Since, every kind of daily use objects will carry these identification tags and embed the object
specific information, it is necessary to take proper privacy measures and prevent unauthorized access.
4) Objects safety and security: The IoT consists of a very large number of perception objects that spread over
some geographic area, it is necessary to prevent the intruder’s access to the objects that may cause physical
damage to them or may change their operation.
5) Data confidentiality and encryption: The sensor devices perform independent sensing or measurements
and transfer data to the information processing unit over the transmission system. It is necessary that the
sensor devices should have proper encryption mechanism to guarantee the data integrity at the information
processing unit.
6) Network security: The data from sensor devices is sent over wired or wireless transmission network. The
transmission system should be able to handle data from large number of sensor devices without causing any
data loss due to network congestion, ensure proper security measures for the transmitted data and prevent
it from external interference or monitoring.

42
Implementation of Fast Fourier Transform Using C++
- Niladri Bhattacharya, B.Tech. 2013
Here is a program to compute fast Fourier transform (FFT) output using C++. FFTs are of great importance to
a wide variety of applications including digital signal processing (such as linear filtering, correlation analysis
and spectrum analysis) and solving partial differential equations to algorithms for quick multiplication of large
integers. Its efficient computation is a topic that has received considerable attention by many
mathematicians, engineers and applied scientists.
Fig. 1: Square wave (time-domain view)
Fig. 2: Square wave (frequency-domain view)

43
Fig. 3: 8-point DFT butterfly structure
In the field of signals and systems, there are two ways of looking at any complex waveform like square wave,
saw-tooth or a practical voice signal: time domain and frequency domain. Depending upon the need to solve
a problem or know the answer of some abrupt behaviour in a system response, we try to switch in between
these two domains. Sometimes, a signal in time domain itself gives answers to many questions but
sometimes we need frequency domain to get the answers. For example, we need frequency domain to know
that a voice signal contains frequency content up to 20 kHz and not beyond that, and also to know that
transmitting it over a telephone requires voice frequency up to 3.4 kHz and the rest of it is of no use. Here
we show an example to explain what it means to look at a signal in two domains. Fig. 1 shows a square signal
in time domain and Fig. 2 shows its frequency domain.
Fig. 4: Output of 8-point FFT in C++

44
Fig. 5: 8-point FFT in MATLAB
We can see from these two figures that frequency domain gives more insight into a signal than time domain.
The peaks in Fig. 2 show the frequency content present in a square wave. The highest peak corresponds to
the fundamental frequency, while the other peaks are called harmonics. By seeing such a frequency-domain
plot of voice signals researchers came out with a decision that up to 3.4 kHz of frequency content is useful,
while the other harmonics have a very small amplitude that can be neglected. The discussion and arguments
so far are equally valid for discrete signals as well.
Fast Fourier transform
Discrete Fourier transform (DFT) is the way of looking at discrete signals in frequency domain. FFT is
an algorithm to compute DFT in a fast way. It is generally performed using decimation-in-time (DIT) approach.
Here we give a brief introduction to DIT approach and implementation of the same in C++.
DIT algorithm. Computational efficiency in the evaluation of DFT is achieved by decomposing the sum of ‘N’
terms intosums containing fewer terms. These decompositionschemes give rise to highly efficientalgorithms
known as fast Fourier transforms. These techniques are based on the ways in which ‘N’ can be factored. For
most part we consider values of ‘N’ that are integral powers of ‘2,’ that is:
N=2m, where ‘m’ is a positive integer.
Here we have taken m=3, so N=8. The signal flow graph in Fig. 3 shows a useful representation of a system
of equations.
Here we present C++ code for implementing 8-bit FFT of a given input sequence using DIT algorithm discussed
in Fig.3.

45
Software program
The software, written in C++, is compiled using Turbo C++ Version 3.0. It was tested on Windows XP SP3
machine. Run the FFT.exe file and enter each signal element of an array followed by pressing Return/Enter
key. Up to eight input elements can be entered.
Fig. 4 shows the screenshot of program output. Here the coefficient of input ‘x’ is (1, 3, 5, 7, 9, 11, 13, 15).
The output is given in (A, B) format, which indicates ‘A’ is real and ‘B’ imaginary component of the complex
number. In order to verify the correctness of our code, we calculated FFT of the same sequence (1, 3, 5, 7, 9,
11, 13, 15) in MATLAB as shown in Fig. 5.
It can be seen that MATLAB outputs the same FFT coefficients as our C++ code, which proves the correctness
of this code.

46
CATOMS: Claytronic Atoms
- Aninda Ghosh, B.Tech. 2016
Claytronics is a form a programmable matter that takes the concept of modular robots to a new extreme.
The concept of modular robots has been around for some time. Previous approaches to modular robotics
sought to create an ensemble of tens or even hundreds of small autonomous robots which could, through
coordination, achieve a global effect not possible by any
single unit. In general the goal of these projects was to
adapt to the environment to facilitate, for example,
improved locomotion. Our work on claytronics departs
from previous work in several important ways. One of
the primary goals of claytronics is to form the basis for
a new media type, pario. Pario, a logical extension of
audio and video, is a media type used to reproduce
moving 3D objects in the real world. A direct result of
our goal is that claytronics must scale to millions of
micron-scale units. Having scaling (both in number and
size) as a primary design goal impacts the work
significantly. The long term goal of our work is to render
physical artifacts with such high fidelity that our senses
will easily accept the reproduction for the original.
When this goal is achieved we will be able to create an
environment, which we call synthetic reality, in which a
user can interact with computer generated artifacts as
if they were the real thing. Synthetic reality has
significant advantages over virtual reality or augmented
reality. For example, there is no need for the user to use any form of sensory augmentation, e.g., head
mounted displays or haptic feedback devices will be able to see, touch, pick-up, or even use the rendered
artifacts. Claytronics is our name for an instance of programmable matter whose primary function is to
organize itself into the shape of an object and render its outer surface to match the visual appearance of that
object. Claytronics is made up of individual components, called catoms.
What is programmable matter?
Programmable matter refers to a technology that will allow one to control and manipulate three-dimensional
physical artifacts (similar to how we already control and manipulate two-dimensional images with computer

47
graphics). In other words, programmable matter will allow us to take a (big) step beyond virtual reality, to
synthetic reality, an environment in which all the objects in a user’s environment (including the ones inserted
by the computer)are physically realized. Note that the idea is not to transport objects nor is it to recreate an
objects chemical composition, but rather to create a physical artifact that will mimic the shape, movement,
visual appearance, sound, and tactile qualities of the original object.
What is a Catom?
Imagine a bracelet or watch that changes into something else when you take it off. Perhaps it becomes a cell
phone, tablet, or computer. Although this scenario may seem like science fiction, this and much more will
soon become reality with a ground-breaking new technology known as CLAYTRONICS.
“Claytronics” is a developing field of electronics reconfigurable nano-scale robots (‘claytronic atoms’ or
catoms) designed to form much larger machines or mechanisms. Also known as ‘Programmable matter’, the
catoms will be sub-millimeter computers that will eventually have the ability to move around, communicate
with each other, change color, electrostatically connect to other catoms to form different shapes. The shapes
made up of catoms could mutate into nearly any object, even replicas of human beings for virtual meetings.
Why it is being developed?
As the Atoms combine to form molecules and form the building blocks of every living organisms, similarly the
micro or nano scale devices can combine to form the shapes of physical entities. This concept known as
“programmable matter” can collaborate to a material called Catoms or “Claytronics atoms”. These Catoms
are the ones that contain sufficient local computation, actuation, storage, energy, sensing and
communication which can be programmed to form interesting dynamic shapes and configurations.
Claytronics is the way of bringing this idea into reality. With claytronics, millions of tiny individual devices-
“claytronics atoms” or “Catoms” would assemble into macro-scale objects, connecting and disconnecting as
they move. The main Moto of developing this particular technology is to revolutionize the communication
between two peers. It’s easy to send 2-D information via internet but using this technology it will be made
possible to render 3d objects according to the 3d information sent.
Claytronics technology is currently being researched by Professor Seth Goldstein and Professor Todd C.
Mowry at Carnegie Mellon University, which is where the term was coined.
What is the basis for the development of catom?
 The Claytronic Atom or Catom would be similar to the look of an atom and is preferred to be spherical
in shape.
 A Catom would have no moving parts and each of the catom will act as an individual.
 It will have electromagnets to attach itself to other Catoms. Thus forming a network.
 Each Catom would contain a fairly powerful processor.

48
 Catom surface would have photocells to sense light and light emitting diodes to allowing it to see
and to change color.
 Computation: Researchers believe that catoms could take advantage of existing microprocessor
technology. Given that some modern microprocessor cores are now under a square millimeter, they
believe that a reasonable amount of computational capacity should fit on the several square
millimeters of surface area potentially available in a 2mm-diameter catom.
 Motion: Although they will move, catoms will have no moving parts. This will enable them to form
connections much more rapidly than traditional microbots, and it will make them easier to
manufacture in high volume. Catoms will bind to one another and move via electromagnetic or
electrostatic forces, depending on the catom size. Imagine a catom that is close to spherical in shape,
and whose perimeter is covered by small electromagnets. A catom will move itself around by
energizing a particular magnet and cooperating with a neighboring catom to do the same, drawing
the pair together. If both catoms are free, they will spin equally about their axes, but if one catom is
held rigid by links to its neighbours, the other will swing around the first, rolling across the fixed
catom's surface and into a new position.
 Power: Catoms must be able to draw power without having to rely on a bulky battery or a wired
connection. Under a novel resistor-network design the researchers have developed, only a few
catoms must be connected in order for the entire ensemble to draw power. When connected catoms
are energized, this triggers active routing algorithms which distribute power throughout the
ensemble.
 Communications: Communications is perhaps the biggest challenge that researchers face in
designing catoms. An ensemble could contain millions or billions of catoms, and because of the way
in which they pack, there could be as many as six axes of interconnection.
First prototype (HARDWARE Aspect)

49
 The current large proof-of-concept Catoms (measuring 4.4 centimeters) connect and move via
magnets, much like the “replicating” robots, operating at scales where electromagnetic or
electrostatic connections are used for reassembling.
 The Catoms could have LCD or LED surfaces able to produce a faintly glowing image, so that what
appeared to be a model made of millions of tiny microbots.
 Backed by the microchip manufacturer Intel, first generation Catoms, measuring 4.4 centimeters in
diameter and 3.6 centimeters in height have been developed.
 The main concerns for the development of this technology are to create the basic modular building
block of claytronics known as the claytronic atom or Catom, and to design and write robust and
reliable software programs that will manage the shaping of the object.
Controller part of catom
The catom has a powerful processor embedded with in itself and the processor will be
dedicated for a single catom only. The tasks like guided localization, actuation of the
magnets, controlling the photo receptors and photo diodes.
Chassis for the catom
The version 8 prototype has a 5 deck chassis the lowest two deck has the magnetic actuator and the top most
two deck contains the controller chip to control the functions. So a very good question comes in mind that
how the power will be
transferred among the catom??
It’s a very interesting question as
the catom will have no external
parts to be connected to them.
The answer to this comes from
the wireless power transfer using
Magnetic Resonant Coupling.
Inductive coupling is an old and well-understood method of wireless power transfer. The source drives a
primary coil, creating a sinusoidal varying magnetic field, which induces a voltage across the terminals of a
secondary coil, and thus transfers power to a load.
This mechanism, responsible for power transfer in a transformer, where the magnetic field is typically
confined to a high permeability core, also functions when the region between the primary and secondary
coils is simply air. Inductive coupling without high permeability cores is used.

50
Power transfer in catom
The greatest challenges facing computer scientists and roboticists today is perhaps the creation of algorithms
and programming language to organize the actions of millions of sub-millimeter scale Catoms in a claytronics.
 Scientists and engineers
have formulated a very
broad-based and in-depth
research program to
develop a complete
structure of software
resources for the creation
and operation of the
densely distributed network of robotic nodes in a claytronic matrix.
 A large, moving shape such as a human replica might contain a billion Catoms. A system with a billion
computer nodes is something on the scale of the entire Internet. Unlike the real Internet, our real
thing is moving. An Internet that sits on a desk!!
Software Development
 PROGRAMMING LANGUAGES: Researchers in the Claytronics project have also created Meld and LDP
(Locally Distributed Predicates). These new languages for declarative programming provide compact
linguistic structures for cooperative management of the motion of millions of modules in a matrix.
 SHAPE SCULPTING: The team’s extensive work on Catom motion, collective actuation and
hierarchical motion planning addresses the need for algorithms that convert groups of Catoms into
primary Copyright 2012 ISA. All rights reserved. www.isa.org Presented at the 58th International
Instrumentation Symposium 4-8 June 2012, San Diego, California structures for building dynamic, 3-
dimensional representations.
 LOCALIZATION: The team’s software researchers are also creating algorithms that enable Catoms to
localize their positions among thousands to millions of other Catoms in an ensemble.
 DYNAMIC SIMULATION: universe. Thus simulated Catoms reflect the natural effects of gravity,
electrical and magnetic forces and other phenomena that will determine the behavior of these
devices in reality. DPRSim also provides a visual display that allows researchers to observe the
behavior of groups of Catoms.
Mechanism for localization
A very crucial step while developing the technology is the process of localization of the CATOMS. Each and
every catom acts as an individual such that it only senses the neighbouring catoms and it orientation
remembering a global picture of the 3d object.

51
Two basic movement approach would be
• Shape sculpting
• Dynamic localization
All the research on catom motion, collective actuation and hierarchical motion planning require shape
sculpting algorithms to convert catoms into the necessary structure, which will give structural strength and
fluid movement to the dynamic ensemble. Meanwhile, localization algorithms enable catoms to localize their
positions in an ensemble.
Applications
 This technology would enable engineers to work remotely in physically hostile environments.
 Surgeons to perform intricate surgery on enlarged claytronic replicas of organs, whilst the actual
organs are being worked upon by a claytronic replica of the surgeon.
 A 3-D Fax machine is a new approach to 3-D faxing. A large number of sub millimetre robot modules
form intelligent clay which can be reshaped via the external application of mechanical forces. The
clay can act as a novel input device, using inter module localization techniques to acquire the shape
of a 3D object by casting.
 Building a moving, sensing, colour changing replica of each person out of nanotech robots makes
every meeting a face-to-face meeting. This is the 3D Video conferencing. We feel that the person,
continents away, as sitting right beside you.
 3D TVs and movies may also be possible using this claytronics.
 It might be useful for producing 3D shapes in the computer-aided design process
 Claytronics cell phone might grow a full-size keyboard, or expand its video display as needed.

52
Working With Temperature Sensors: A Guide
- Ankita Gandhi, B.Tech. 2015
Temperature is the most often measured environmental quantity and many biological, chemical, physical,
mechanical and electronic systems are affected by temperature.
Some processes work well only within a narrow range of
temperatures. So proper care must be taken to monitor and protect
the system.
When temperature limits are exceeded, electronic components
and circuits may be damaged by exposure to high temperatures.
Temperature sensing helps to enhance circuit stability. By sensing
the temperature inside the equipment, high temperature levels can
be detected and actions can be taken to reduce system temperature, or even shut the system down to avert
disasters. Several temperature sensing techniques are used currently. The most common of these are
thermocouples, thermistors and sensor integrated circuits (ICs). What is most suitable for your application
depends on the required temperature range, linearity, accuracy, cost, features and the ease of designing the
necessary support circuitry.
Thermocouples
A thermocouple consists of two dissimilar metals joined together at one end, to produce a small unique
voltage at a given temperature. The thermoelectric voltage, resulting from the temperature difference from
one end of the wire to the other, is actually the sum of all the voltage differences
along the wire from end to end. Thermocouples are available in different
combinations of metals or calibrations. The four most common calibrations are J, K, T and E. Each calibration
has a different temperature range and environment, although the maximum temperature varies with the
diameter of the wire used in the thermocouple. For example, a ‘type J’ thermocouple is made from iron and
constantan wires. Thermocouples are very popular because of their low thermal mass and wide operating
temperature range, which can extend to about 1700°C with common types. However, sensitivity of
thermocouples is rather small (of the order of tens of microvolts per ºC). A low-offset amplifier is needed to
produce a usable output voltage.
Thermistors
Thermistors are special solid temperature sensors that behave like temperature-sensitive electrical resistors.
These are generally composed of semiconductor materials. There are basically two types of thermistors—
negative temperature coefficient (NTC), which are used mostly in temperature sensing and positive

53
temperature coefficient (PTC), which are used mostly in electric current control.
Thermistor exhibits a change in electrical resistance with a change in its temperature. The resistance is
measured by passing a small, measured direct current through it and measuring the voltage drop produced
thereby. When it comes to NTC-type, the negative coefficient can be as large as several per cent per ºC,
allowing the thermistor circuit to detect minute changes in temperature, which could not be
observed with a thermocouple circuit.
Low-cost thermistors often perform simple measurement (and trip-point detection) functions
in low-end systems. Low-precision thermistors are often inexpensive. You can find thermistors that will work
over a temperature range from about -100°C to +550°C, although most are rated for maximum operating
temperatures from 100°C to 150°C. Simple thermistor-based set-point thermostat or controller applications
can be implemented with very few components. Just the thermistor, a comparator and a few other
components can do the job. As thermistors are extremely non-linear devices that are highly dependent upon
process parameters, and their performance may be degraded by self-heating, these have drawbacks in some
applications. For example, resistance temperature function of a thermistor is very non-linear, so if wide range
of temperatures are to be measured, you’ll find it necessary to perform substantial linearization.
Sensor ICs
There are a wide variety of temperature sensor ICs that are available to simplify the broadest possible range
of temperature monitoring challenges. These silicon temperature sensors differ significantly from the above
mentioned types in a couple of important ways.
The first is operating temperature range. A temperature sensor IC can operate over the nominal IC
temperature range of -55°C to +150°C. The second major difference is functionality. A silicon temperature
sensor is an integrated circuit, and can therefore include extensive signal processing circuitry within the same
package as the sensor. There is no need to add compensation (or linearization) circuits for temperature
sensor ICs.
Some of these are analogue circuits with either voltage or current output. Others combine analogue-sensing
circuits with voltage comparators to provide alert functions. Some other sensor ICs combine analogue-
sensing circuitry with digital input/output and control registers, making them an ideal solution for
microprocessor-based systems. Digital output sensor usually contains a temperature sensor, analog-to-
digital converter (ADC), a two-wire digital interface and registers for controlling the IC’s operation.
Temperature is continuously measured and can be read at any time. If desired, the host processor can
instruct the sensor to monitor temperature and take an output pin high (or low) if temperature exceeds a
programmed limit. Lower threshold temperature can also be programmed and the host can be notified when
temperature has dropped below this threshold. Thus, digital output sensor can be used for reliable
temperature monitoring in microprocessor-based systems.

54
How to use?
A temperature sensor produces an analogue or digital output whose strength depends on the temperature
of the sensor. Heat is conducted to the sensing element through the sensor’s package and its metal leads. In
general, a sensor in a metal package will have a dominant thermal path through the package. For sensors in
plastic packages, the leads provide the dominant thermal path. Therefore a board-mounted IC sensor will do
a fine job of measuring the temperature of the circuit board.
If it’s needed to measure the temperature of something other than the circuit board, it should be ensured
that the sensor and its leads are at the same temperature as the object you wish to measure. This usually
involves making a good mechanical (and thermal) contact by attaching the sensor and its leads to the object
being measured with thermally-conductive epoxy.
If a liquid’s temperature is to be measured, the sensor can be mounted inside a sealed-end metal tube and
dipped into a bath, or screwed into a threaded hole in a tank. Temperature sensors and any accompanying
wiring and circuits must be kept insulated and dry, to avoid leakage and corrosion.
Any linear circuit connected to wires in an uncongenial environment can have its performance adversely
affected by intense electromagnetic sources such as relays, radio transmitters, motors with arcing brushes
etc., as its wiring can act as an aerial and the internal junctions can act as rectifiers. In such cases, a small
bypass capacitor from the power supply pin to ground rail helps clean up power supply noise.
Smart cooling fan controller, based on the LM56 temperature sensor IC, that turns the fan on at one temperature,
then increases its speed if temperature rises above a second threshold
Output filtering can be added as well. When using analogue sensors that should not directly drive large
capacitive loads, the output filter capacitor can be isolated with a low-value resistor (like a zobel network) in
series with the capacitor. A three-terminal sensor needs three wires for power, ground and output signals.
When sensing the temperature in a remote location, it is desirable to minimise the number of wires between
the sensor and the main circuit board. In such situations you can use a two-terminal sensor. Moving to two
wires means that power and signal must coexist on the same wires.

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